Method for forming an apertured web

ABSTRACT

A method for forming an apertured web which may be used as a topsheet on a disposable absorbent article, such as a diaper. The web ( 240 ) is fed in as machine direction through a first nip ( 250 ) formed by a pair of rollers one of the rollers having a smooth outer surface and the other roller having an outer surface with a plurality of projections extending from it&#39;s outer surface. At least one of the rollers of the first nip ( 250 ) is heated. The first nip ( 250 ) apertures the web with a plurality of apertures each having a fused perimeter. The web ( 240 ) is then cooled to solidify the fused perimeter of the apertures. The web ( 240 ) is then fed through a second nip ( 280 ) formed by a pair of rollers to break the solidified fused perimeter of the apertures. One of the rollers of the second nip ( 280 ) has an outer surface with a plurality of grooves.

FIELD OF THE INVENTION

This invention relates to a method for forming an apertured web, andmore particularly to a method for forming an apertured web suitable foruse as a topsheet on a disposable absorbent article.

BACKGROUND OF THE INVENTION

Disposable absorbent articles such as diapers and adult incontinenceproducts are well known in the art. Such disposable absorbent articlescollect and retain urine and fecal material deposited thereon by thewearer.

To date, most attempts in the art to handle the urine and fecal materialcollected and retained in the disposable absorbent article have beendirected to handling urine. Dealing with fecal material collected by thedisposable absorbent article is simply more difficult than dealing withurine, due to the complex rheology of low-viscosity fecal material.

Exemplary of the urine handling prior art are several attempts toprovide disposable absorbent articles having a first topsheet whichfaces towards and contacts the body of the wearer, and a secondarytopsheet under the first topsheet, which either absorbs urine, ortransfers the urine to an underlying core for storage until thedisposable absorbent article is removed from the wearer.

Typically, the first topsheet and secondary topsheet have differentmaterial properties. The secondary topsheet may have a smaller pore sizethan the first topsheet, to assist in transfer of the urine through thetopsheet. The first topsheet may be hydrophobic and more resilient whenwetted than the secondary topsheet, in order to pass fluids through thefirst topsheet to the secondary topsheet.

In yet another attempt in the prior art, the disposable absorbentarticle has a first topsheet, secondary topsheet and core. The secondarytopsheet consists essentially of meltblown hydrophilic fibers and has apore size greater than the pore size of the core. This arrangementallegedly allows the secondary topsheet to rapidly receive multipleliquid insults and distribute the liquid in the X-Y plane prior toabsorption by the core. In yet another attempt, improved verticalwicking capability for urine has been allegedly achieved using inflatedcellulose fibers which are free of a surface finish or are crosslinkedto one another.

In another attempt in the prior art, an absorbent core suitable foracquiring and containing liquids such as urine in a particularlyeffective and efficient manner comprises multiple layers. The firstlayer, which is closest to the wearer, comprises hydrophilic fibrousmaterial and has an acquisition zone of a relatively lower averagedensity than other portions of this layer, in order to quickly acquiredischarged liquids. Below the first layer is a liquid handling layercomprising a resilient, low density high void volume material that ismoisture insensitive in order to rapidly acquire liquid insults intoitself through the acquisition zone and distribute these liquidsthroughout the liquid handling layer to a storage layer. The storagelayer comprises a combination of fibrous material and discrete particlesof absorbent gelling material, and allows the liquid handling layer tobe drained of the liquids it has acquired, so that the liquid handlinglayer may have sufficient capacity to acquire and distribute subsequentloadings of liquids.

Examples of such attempts in the prior art include U.S. Pat. No.4,047,531 issued Sep. 13, 1977 to Karami; U.S. Pat. No. 4,798,603 issuedJan. 17, 1989 to Meyer et al.; U.S. Pat. No. 5,037,409 issued Aug. 6,1991 to Chen et al.; U.S. Pat. No. 5,124,197 issued Jun. 23, 1992 toBernardin et al.; and U.S. Pat. No. 5,134,007 issued Jul. 28, 1992 toReising et al.

Of course, absorbent gelling materials are also now well known in theprior art for their urine handling capability. Absorbent gellingmaterials are polymeric materials capable of absorbing large quantitiesof fluids, such as urine, and retaining such absorbed fluids undermoderate pressure. The effectiveness of the absorbent gelling materialsis quite dependent upon the form, position, and weight percentage of theabsorbent gelling materials which are incorporated into the core of thedisposable absorbent article.

Recent attempts have been made in the art to provide absorbent gellingmaterials which have the ability to swell against pressure. Theseteachings allege to provide the advantage that the absorbent gellingmaterials absorb fluid under actual pressures exerted by the body duringuse. Yet other teachings in the art provide absorbent gelling materialshaving a particular free swell rate and absorbency under load. Allegedadvantages of such an absorbent gelling materials are lower volume andmass with approximately the same absorbent capacity, the ability torapidly absorb a discharged liquid under pressures typically encounteredduring use, and the ability to retain the absorbed liquid underpressures typically encountered during use.

In another prior attempt, U.S. Pat. No. 4,704,112 issued to Suzuki etal. discloses a facing comprising a nonwoven fabric having two differentlayers of different fiber compositions. The upper layer has a pattern ofapertures therein and is made from hydrophobic fibers and the lowerlayer has no apertures and is made from hydrophilic fibers.

Examples of such attempts in the prior art include U.S. Pat. No.5,147,343 issued Sep. 15, 1992 to Kellenberger and U.S. Pat. No.5,149,335 issued Sep. 22, 1992 to Kellenberger et al.

However, all of these attempts to handle urine do little, if anything,to improve handling of low-viscosity fecal material which may also bepresent in the disposable absorbent article. Attempts to deal with fecalmaterial include providing a first topsheet which conforms closely tothe wearer and has an aperture. The aperture is hopefully registeredwith the anal opening, so that fecal material passes therethrough into avoid space. The first topsheet may comprise various elastic panels inorder to closely conform to the skin of the wearer, and/or may havelinear elastic strands. Improvements have been made in this area of theprior art, such as optimizing the material properties of the firsttopsheet. Such optimization makes the first topsheet more comfortable tothe wearer and allows a single disposable absorbent article to fit alarger range of sizes of wearers.

Yet other attempts have been made in this area of the prior art toprovide an absorbent core with a hole therein, in order to receive thefecal material. The hole may be oblate shaped, so that it is longer andnarrower than the aperture in the first topsheet, or may be diamondshaped. The hole in the core may be positioned below an aperture whichhas elastic strips around its edge.

Improvements to this genre of the prior art disposable absorbentarticles also include the addition of spacers. Spacers may be interposedbetween the first topsheet and the core, in order to ensure a void spaceis present to receive the fecal material.

Yet other attempts have been made in this genre of the prior art toprovide barriers which limit the movement of fecal material toparticular portions of the disposable absorbent article. The barrierslimit the contact of the fecal material to a lesser portion of the skinof the wearer, than a comparable disposable absorbent article which hasno barriers.

Still other attempts in the prior art provide barrier leg cuffs whichare upstanding from the plane of the topsheet. The barrier leg cuffsprevent fecal material from breaching the perimeter of the disposableabsorbent article.

Examples of such attempts to handle fecal material include U.S. Pat. No.4,892,536 issued Jan. 9, 1990 to DesMarais et al.; U.S. Pat. No.4,909,803 issued Mar. 20, 1990 to Aziz et al.; U.S. Pat. No. 4,968,312issued Nov. 6, 1990 to Khan; commonly assigned U.S. Pat. No. 4,990,147issued Feb. 5, 1991 to Freeland; commonly assigned U.S. Pat. No.5,037,416 issued Aug. 6, 1991 to Allen et al.; U.S. Pat. No. 5,062,840issued Nov. 5, 1991 to Holt et al.; commonly assigned U.S. Pat. No.5,171,236 issued Dec. 15, 1992 to Dreier et al.; and European PatentApplication 0,355,740 A2 published Feb. 28, 1990 to Enloe.

However, none of these attempts to handle fecal material solve theproblem of low-viscosity fecal material which is predominately prevalentin younger children, particularly those who are breast fed.Low-viscosity fecal material easily migrates within the disposableabsorbent article under the influences of gravity and motion or pressureby the wearer.

The migration of the fecal material often moves it towards the perimeterof the disposable absorbent article, increasing the likelihood ofleakage. The migration of the fecal material also smears it against theskin of the wearer, making cleanup more difficult. In order to clean thewearer, the caretaker must wipe the entire area of the skin which hasencountered the fecal material and typically has to deal with arelatively large soiled area.

One attempt in the art to handle low-viscosity fecal material is foundin U.S. Pat. application Ser. No. 08/076,713 filed Jun. 11, 1993 in thename of Roe. This application is a disposable absorbent article having afirst topsheet with a high trans-topsheet penetration overlaying asecondary topsheet having a lesser trans-topsheet penetration.

BRIEF SUMMARY OF THE INVENTION

The invention is a method for forming an apertured web which may be usedas a topsheet on a disposable absorbent article, such as a diaper. Theweb is fed in a machine direction through a first nip formed by a pairof rollers one of the rollers having a smooth outer surface and theother roller having an outer surface with a plurality of projectionsextending from it's outer surface. At least one of the rollers formingthe first nip is heated, preferably both rollers are heated. As the webpasses through the first nip a plurality of apertures are created eachhaving a fused perimeter. The web is cooled to solidify the fusedperimeter of the apertures. The web is then fed through a second nipformed by a pair of rollers to break the solidified fused perimeter ofthe apertures. One of the rollers of the second nip has an outer surfacecomprising a plurality of grooves.

The web may be fed through a third nip formed by a pair of rollers tofurther break the fused perimeter of the apertures. One of the rollersof the third nip has an outer surface comprising a plurality of grooves.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims pointing out anddistinctly claiming the present invention, it is believed the same willbe better understood by the following drawings taken in conjunction withthe accompanying specification wherein like components are given thesame reference number.

FIG. 1 is a top plan view, shown partially in cutaway, of a disposablediaper having a topsheet constructed of the apertured web of the presentinvention.

FIG. 2 is a cross-sectional view of the apertured web topsheet shown inFIG. 1.

FIG. 3 is a top plan view of a disposable diaper having a topsheetconstructed of another embodiment of the web of the present invention.

FIG. 4 is a simplified schematic illustration of a process for formingthe apertured web of the present invention.

FIG. 5 is an enlarged overhead plan view illustration of the groovedroll of FIG. 4.

FIG. 6 is a simplified schematic illustration of another process forforming the apertured web of the present invention.

FIG. 7 is an enlarged overhead plan view illustration of the groovedroll of the third nip of FIG. 6.

FIG. 8 is a simplified schematic illustration of another process forforming the apertured web of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term “absorbent article” refers to devices whichabsorb and contain body exudates, and, more specifically, refers todevices which are placed against or in proximity to the body of thewearer to absorb and contain the various exudates discharged from thebody. The term “disposable” is used herein to describe absorbentarticles which are not intended to be laundered or otherwise restored orreused as an absorbent article (i.e., they are intended to be discardedafter a single use and, preferably, to be recycled, composted orotherwise disposed of in an environmentally compatible manner). A“unitary” absorbent article refers to absorbent articles which areformed of separate parts united together to form a coordinated entity sothat they do not require separate manipulative parts like a separateholder and liner.

An absorbent article utilizing the apertured web of the presentinvention as a topsheet thereon is the unitary disposable absorbentarticle, diaper 20, shown in FIG. 1. As used herein, the term “diaper”refers to an absorbent article generally worn by infants and adultincontinent persons and is worn about the lower torso of the wearer. Theweb of the present invention may also be used as a topsheet on otherabsorbent articles such as incontinence briefs, incontinenceundergarments, absorbent inserts, diapers holders and liners, femininehygiene garments, and the like.

While the present invention will be described in the context ofproviding a web suitable for use as a topsheet on a disposable absorbentarticle, the present invention is in no way limited to such application.The description of the apertured web and its use as a topsheet willallow one skilled in the art to readily adapt the invention to otherdevices and for other uses.

FIG. 1 is a plan view of the diaper 20 of the present invention in itsflat-out, uncontracted state (i.e., with elastic induced contractionpulled out) with portions of the structure being cut-away to moreclearly show the construction of the diaper 20 and with the portion ofthe diaper 20 which faces or contacts the wearer, the inner surface,oriented towards the viewer. As shown in FIG. 1, the diaper 20preferably comprises a liquid pervious topsheet 24; a liquid imperviousbacksheet 26 joined with the topsheet 24; and an absorbent core 28intermediate the topsheet 24 and the backsheet 26. The diaper 20 mayfurther comprise elasticized side panels (not shown); elasticized legcuffs (not shown); an elastic waist feature (not shown); and a fasteningsystem with tape tabs generally multiply designated as 36.

The diaper 20 is shown in FIG. 1 to have a first waist region 27juxtaposed with the front of the wearer while the diaper 20 is beingworn, a second waist region 29 opposed to the first waist region 27 andjuxtaposed with the back of the wearer while the diaper 20 is beingworn, a crotch region 31 positioned between the first waist region 27and the second waist region 29, and a periphery which is defined by theouter edges of the diaper 20 in which the longitudinal edges aredesignated 33 and the end edges are designated 35. The inner surface ofthe diaper 20 comprises that portion of the diaper 20 which is adjacentto the wearer's body during use (i.e., the inner surface generally isformed by at least a portion of the topsheet 24 and other componentsjoined to the topsheet 24). The outer surface comprises that portion ofthe diaper 20 which is positioned away from the wearer's body (i.e., theouter surface generally is formed by at least a portion of the backsheet26 and other components joined to the backsheet 26) during use.

FIG. 1 shows an embodiment of the diaper 20 in which the topsheet 24 andthe backsheet 26 have length and width dimensions generally larger thanthose of the absorbent core 28. The topsheet 24 and the backsheet 26extend beyond the edges of the absorbent core 28 to thereby form theperiphery of the diaper 20. While the topsheet 24, the backsheet 26, andthe core 28 may be assembled in a variety of well known configurations,preferred diaper configurations are described generally in U.S. Pat. No.3,860,003 entitled “Contractable Side Portions for Disposable Diaper”which issued to Kenneth B. Buell on Jan. 14, 1975; and U.S. Pat. No.5,151,092, “Absorbent Article With Dynamic Elastic Waist Feature HavingA Predisposed Resilient Flexural Hinge”, issued to Kenneth B. Buell etal. Sep. 29, 1992; each of which is incorporated herein by reference.

The absorbent core 28 may be any absorbent means which is generallycompressible, conformable, non-irritating to the wearer's skin, andcapable of absorbing and retaining liquids such as urine and othercertain body exudates. As shown in FIG. 1, the absorbent core 28 has agarment surface, a body surface, side edges, and waist edges. Theabsorbent core 28 may be manufactured in a wide variety of sizes andshapes (e.g., rectangular, hourglass, “T”-shaped, asymmetric, etc.) andfrom a wide variety of liquid-absorbent materials commonly used indisposable diapers and other absorbent articles such as comminuted woodpulp which is generally referred to as airfelt. Examples of othersuitable absorbent materials include creped cellulose wadding; meltblownpolymers including coform; chemically stiffened, modified orcross-linked cellulosic fibers; tissue including tissue wraps and tissuelaminates; absorbent foams; absorbent sponges; superabsorbent polymers;absorbent gelling materials; or any equivalent material or combinationsof materials.

The configuration and construction of the absorbent core 28 may also bevaried (e.g., the absorbent core 28 may have varying caliper zones, ahydrophilic gradient, a superabsorbent gradient, or lower averagedensity and lower average basis weight acquisition zones; or maycomprise one or more layers or structures). The total absorbent capacityof the absorbent core 28 should, however, be compatible with the designloading and the intended use of the diaper 20. Further, the size andabsorbent capacity of the absorbent core 28 may be varied to accommodatewearers ranging from infants through adults.

Exemplary absorbent structures for use as the absorbent core 28 aredescribed in U.S. Pat. No. 4,610,678 entitled “High-Density AbsorbentStructures” issued to Weisman et al. on Sep. 9, 1986; U.S. Pat. No.4,673,402 entitled “Absorbent Articles With Dual-Layered Cores” issuedto Weisman et al. on Jun. 16, 1987; U.S. Pat. No. 4,888,231 entitled“Absorbent Core Having A Dusting Layer” issued to Angstadt on Dec. 19,1989; and U.S. Pat. 4,834,735, entitled “High Density Absorbent MembersHaving Lower Density and Lower Basis Weight Acquisition Zones”, issuedto Alemany et al. on May 30, 1989. Each of these patents is incorporatedherein by reference.

The backsheet 26 is positioned adjacent the garment surface of theabsorbent core 28 and is preferably joined thereto by attachment means(not shown) such as those well known in the art. As used herein, theterm “joined” encompasses configurations whereby an element is directlysecured to the other element by affixing the element directly to theother element, and configurations whereby the element is indirectlysecured to the other element by affixing the element to intermediatemember(s) which in turn are affixed to the other element.

For example, the backsheet 26 may be secured to the absorbent core 28 bya uniform continuous layer of adhesive, a patterned layer of adhesive,or an array of separate lines, spirals, or spots of adhesive. Adhesiveswhich have been found to be satisfactory are manufactured by H. B.Fuller Company of St. Paul, Minn. and marketed as HL-1258. Theattachment means will preferably comprise an open pattern network offilaments of adhesive as is disclosed in U.S. Pat. No. 4,573,986entitled “Disposable Waste-Containment Garment”, which issued toMinetola et al. on Mar. 4, 1986, more preferably several lines ofadhesive filaments swirled into a spiral pattern such as is illustratedby the apparatus and methods shown in U.S. Pat. No. 3,911,173 issued toSprague, Jr. on Oct. 7, 1975; U.S. Pat. No. 4,785,996 issued to Ziecker,et al. on Nov. 22, 1978; and U.S. Pat. No. 4,842,666 issued to Wereniczon Jun. 27, 1989. Each of these patents is incorporated herein byreference. Alternatively, the attachment means may comprise heat bonds,pressure bonds, ultrasonic bonds, dynamic mechanical bonds, or any othersuitable attachment means or combinations of these attachment means asare known in the art.

The backsheet 26 is impervious to liquids (e.g., urine) and ispreferably manufactured from a thin plastic film, although otherflexible liquid impervious materials may also be used. As used herein,the term “flexible” refers to materials which are compliant and willreadily conform to the general shape and contours of the human body.

The backsheet 26 prevents the exudates absorbed and contained in theabsorbent core 28 from wetting articles which contact the diaper 20 suchas bedsheets and undergarments. The backsheet 26 may thus comprise awoven or nonwoven material, polymeric films such as thermoplastic filmsof polyethylene or polypropylene, or composite materials such as afilm-coated nonwoven material. Preferably, the backsheet 26 is athermoplastic film having a thickness of about 0.012 mm (0.5 mil) toabout 0.051 mm (2.0 mils). Particularly preferred materials for thebacksheet 26 include RR8220 blown films and RR5475 cast films asmanufactured by Tredegar Industries, Inc. of Terre Haute, Ind. Thebacksheet 26 is preferably embossed and/or matte finished to provide amore clothlike appearance. Further, the backsheet 26 may permit vaporsto escape from the absorbent core 28 (i.e., be breathable) while stillpreventing exudates from passing through the backsheet 26.

The topsheet 24 is juxtaposed with, but not necessarily adjacent thebody surface of the absorbent core 28, and is preferably joined to thebacksheet 26 or absorbent core 28 by means such as those well known inthe art. Suitable attachment means are described above with respect tojoining the backsheet 26 to the absorbent core 28. In a preferredembodiment of the present invention, the topsheet 24 and the backsheet26 are joined directly to each other in the diaper periphery.

Referring now to FIGS. 1 and 2, the topsheet 24 comprises a web 40constructed of a liquid pervious material. The web 40 is compliant, softfeeling, and non-irritating to the wearer's skin. The web 40 ispreferably a liquid pervious nonwoven web. The nonwoven web is a fibrousmaterial formed from fusible polymeric fibers or filaments. The nonwovenweb can be formed from any of the following polymers: polyamides,polypropylene, polypropylene copolymers, bi-component, polyethylene,polyethylene-terephthalate, combinations thereof, and the like. Suitablematerials include dry laid and carded webs, air laid and random webs,spunbonded webs, meltblown webs, spunlaced webs, and through-air orcalendar bonded webs. Alternatively, the nonwoven web can belatex-bonded via saturation bonding, gravure printing, screen printing,spray or foam bonding. Still further, the nonwoven web may be bondedwith combinations of the above techniques, such as latex bonded andcalendar bonded webs or other suitable combinations. The fibers can beof various sizes with fibers having a denier between about 1 and 18being preferred. The web 40 preferably has a basis weight of from about5 gsm to 100 gsm, more preferably of from about 5 gsm to about 60 gsm.The web 40 preferably has a caliper of from about 0.1 mm to 5.0 mm, andmore preferably of from about 0.1 mm to about 2.0 mm.

The web 40 has a plurality of apertures 46 with an effective aperturesize of at least 0.2 square millimeters, more preferably, the pluralityof apertures have an effective aperture size of at least 0.5 squaremillimeters, even more preferably, the plurality of apertures have aneffective aperture size of at least 1.0 square millimeter, and mostpreferably, the plurality of apertures have an effective aperture sizeof at least 2.0 square millimeters. Effective apertures are those whichhave a gray level of 18 or less on a standard gray level scale of 0-255,under the image acquisition parameters described below.

The web 40 preferably has an effective open area of at least 10 percent,more preferably the web 40 has an effective open area of at least 15percent, even more preferably, the web 40 has an effective open area ofat least 20 percent, and most preferably the web 40 has an effectiveopen area of at least 25 percent.

The effective aperture size and effective open area are determined bythe following procedure using the image analysis described below. Theprocedure has three principal steps: image acquisition, i.e., obtainingrepresentative images of areas on the surface of the web 40; imagemeasurement, i.e., measuring the percentage open area of an image and ofindividual apertures and their perimeters; and data analysis, i.e.,exporting the percentage open area, individual aperture area, andperimeter measurements to a spreadsheet where frequency distributions,sum of area distributions, and hydraulic radius computations are made.

An image analysis system having a frame grabber board, microscope,camera and image analysis software is utilized. A model DT2855 framegrabber board available from Data Translation of Marlboro, Mass. isprovided. A VH5900 monitor microscope, a video camera, having aVH50 lenswith a contact type illumination head available from the Keyence Companyof Fair Lawn, N.J. are also provided and used to acquire an image to besaved to computer file. The Keyence microscope acquires the image andthe frame grabber board converts the analog signal of this image intocomputer readable digital format. The image is saved to computer fileand measured using suitable software such as the Optimas Image Analysissoftware, version 3.1, available from the BioScan Company of Edmaons,Wash. In order to use the Optimas Image Analysis software, the computershould have Windows software, version 3.0 or later, available from theMicrosoft Corporation of Redmond, Wash. And also have a CPU at leastequivalent to the Intel 80386. Any suitable desk top PC may be used,with a 486 DX33 type PC having been found to be particularly suitable.Images being saved to and recalled from file were displayed on a SonyTrinitron monitor model PVM-1343MO with a final display magnification ofabout 50×.

The image acquisition step, noted above requires 10 different regionsfrom a representative sample of material to be tested. Each region isrectangular, measuring about 5.8 millimeters by 4.2 millimeters. Thesample is placed on a black mat board to increase the contrast betweenthe apertures and the portion of the sample which defines the apertures.The mean gray level and standard deviation of the black mat board were16 and 4, respectively.

Images are acquired with room lights off using the Keyence monitormicroscope mounted on a copystand directly above the sample. The Keyencelight source illuminating the sample is adjusted and monitored with theOptimas software to measure the mean gray level and standard deviationof a 0.3 density wedge on a Kodak Gray Scale available from EastmanKodak Company of Rochester, N.Y. The control of Keyence light source isadjusted so that the mean gray level of the illuminated wedge is 111±1and the standard deviation is 10±1. All images were acquired during asingle time period, and the Keyence light source is monitored bymeasuring the mean gray level and standard deviation of the wedgethroughout the image acquisition process.

In measuring an individual aperture, only the effective aperture size isof interest. Measuring the effective aperture size quantifies theaperture size intended to contribute to the porosity of the material,and account for contributions of fibers and fiber bundles which traversean area intended to be an aperture. An effective aperture is any holethrough the material having a gray level less than or equal to 18 usingimage acquisition parameters as described herein. Thus, an intendedaperture may be divided into plural effective apertures by traversefibers.

The image analysis software is calibrated in millimeters by a rulerimage acquired from the sample images. A 3 by 3 pixel averaging filterfound in the Optimas 3.1 Image menu is applied to each saved image toreduce noise. The apertures are detected in the gray level range of 0through 18. An aperture which is not fully contained within the 5.8 by4.2 viewing area is not considered in the individual area and perimetermeasurements. Therefore, area and perimeter averages and distributionsare not affected by apertures which are not wholly contained within thefield of view.

However, individual apertures which could not be fully viewed in theimage are included in the percentage open area calculation. Thisdifference occurs because the percent open area is simply the image ofpixel ratios from 0 through 18 to the total number of pixels in theimage. Areas having a gray level 19 or greater were not counted in theopen area calculation.

The percentage open area for the average of 10 images for each materialis measured using the Optimas Image Analysis software. The percentageopen area is defined as the ratio of the number of pixels having a graylevel from 0 through 18 to the total number of pixels for the image. Thepercentage open area is measured for each image representing oneparticular region from a sample. The percentage open area from each ofthe 10 individual images is then averaged to yield a percentage openarea for the entire sample.

The data analysis is conducted by an Excel spreadsheet, also availablefrom the Microsoft Corporation of Redmond, Wash. The Excel spreadsheetorganized the percentage open area, aperture area, and apertureperimeter measurements obtained from the Optimas software. Sampleaverages and standard deviations, size and frequency distributions ofindividual aperture areas and hydraulic radius computations (areadivided by perimeter) for individual apertures are obtained using thespreadsheet.

Distributions of individual aperture area are also computed using theExcel spreadsheet. The apertures are sorted into bins of certain sizeranges. The number of aperture areas falling into certain size ranges ofinterest is determined as well as the sum of the areas within eachrange. The ranges are set in increments of 0.05 square millimeters.These areas are expressed as a percentage of the total open area of thesample. The frequency and sum of the area distributions are obtained bycombining individual aperture measurements from all 10 images for eachsample.

The apertures 46 in the web 40 can vary in size, shape and pattern.Examples of some possible shapes include but are not limited tocircular, square, rectangular, oval, triangular, dog-bone, star, oblong,etc. The apertures 46 can be arranged in either a systematic, uniform orrandom pattern. A systematic pattern, with similarly sized apertures ispreferred.

Referring now to FIG. 3, the topsheet 124 on the diaper 120 comprisesapertured web 140. As can be seen in FIG. 3, the web 140 is onlyapertured in the rear or back waist region 129 of the diaper 120. Theweb 140 may be apertured in any suitable manner to provide the desiredbenefits in certain portions or regions of the diaper 120. For example,the web 140 may be apertured in only the crotch region 131 or only thefront waist region 127, any combination of two regions, portions of anyone region, or portions of several regions.

Referring now to FIG. 4 there is shown a schematic illustration of aprocess 200 for forming the apertured web of the present invention. Amaterial 240 is unwound from a supply roll 210 and travels in thedirection indicated by the arrows associated therewith, i.e., in themachine direction, as the supply roll 210 rotates in the directionindicated by the arrows associated therewith.

Instead of being unwound from a supply roll the material may be feddirectly from a forming apparatus, e.g., a carding apparatus, a cardingand calendaring apparatus, a spunbonding apparatus, a spunbonding andcalendaring apparatus, a meltblowing apparatus, a meltblowing andcalendaring apparatus, to the first nip 250.

The web 240 is fed through the first nip 250 of the aperturing apparatus252 formed by rollers 254 and 260. Roller 260 has a smooth outer surface262. Roller 260 is preferably constructed of steel. Roller 260 may beconstructed of other materials, for example, rubber. Roller 254 includesa plurality of projections 258 extending about it's outer surface 256.Roller 254 is preferably constructed of steel.

Rollers 254 and 260 preferably rotate at the same velocity. While atleast one of the rollers 254 and 260 is heated, preferably, both rollers254 and 260 are heated. Preferably, roller 254 is heated to have ahigher temperature than roller 260. As the web 240 passes through thefirst nip 250 it is apertured. As the web is apertured it is heatedabove its melting point such that at least a portion of the aperturesperimeter is fused.

After the web 240 has been apertured by apparatus 252, the web 240 isthen cooled to set the web after leaving apparatus 252. In FIG. 4, theweb 240 is shown to be cooled by blowing cold air onto the web 240 fromblower 270. Of course other known techniques may be used to cool the web240. Cooling the web also solidifies the fused material extending aboutthe perimeter of the apertures.

After cooling, the apertured web 240 is fed through the second nip 280formed by rollers 282 and 284. Rollers 282 and 284 preferably rotate atthe same velocity. Rollers 282 and 284 break the solid fused materialwhich extends about the perimeter of the apertures. Breaking the solidfused material increases the softness of the web 240 .

Roller 284 has a smooth outer surface and is preferably constructed of asoft material such as rubber, polyamide, or other polymeric material.Referring now to FIG. 5, the outer surface 281 of roller 282 comprises aplurality of grooves 283. Grooves 283 extend about the outer surface 281in a direction parallel to the machine direction. The grooves may alsoextend in other directions. The size, spacing, shape and number ofgrooves may be selected so as to provide the desired softness in the web240 as the grooves help to break the solid fused material which extendsabout the perimeter of the apertures. Roller 282 is preferablyconstructed of steel.

The peripheral linear speed of rollers 282 and 284 is preferably greaterthan the peripheral linear speed of rollers 254 and 260 therebytensioning the material between the two sets of rollers. By adjustingthe speeds of the rollers, the material is tensioned such that it necksa desired amount.

From the second nip 280 the web 240 is wound on take-up roll 290.

Referring now to FIG. 6, there is shown a schematic illustration ofanother process 300 for forming the apertured web of the presentinvention. A material 340 is unwound from a supply roll 310 and travelsin the direction indicated by the arrows associated therewith, i.e., inthe machine direction, as the supply roll 310 rotates in the directionindicated by the arrows associated therewith.

Instead of being unwound from a supply roll the material may be feddirectly from a forming apparatus, e.g., a carding apparatus, a cardingand calendaring apparatus, a spunbonding apparatus, a spunbonding andcalendaring apparatus, a meltblowing apparatus, a meltblowing andcalendaring apparatus, to the first nip 350.

The web 340 is fed through the first nip 350 of the aperturing apparatus352 formed by rollers 354 and 360. Roller 360 has a smooth outer surface362. Roller 360 is preferably constructed of steel. Roller 360 may beconstructed of other materials, for example, rubber. Roller 354 includesa plurality of projections 358 extending about it's outer surface 356.Roller 354 is preferably constructed of steel.

Rollers 354 and 360 preferably rotate at the same velocity. While atleast one of the rollers 354 and 360 is heated, preferably, both rollers354 and 360 are heated. Preferably, roller 354 is heated to have ahigher temperature than roller 360. As the web 340 passes through thefirst nip 350 it is apertured. As the web is apertured it is heatedabove its melting point such that at least a portion of the aperturesperimeter is fused.

After the web 340 has been apertured by apparatus 352, the web 340 isthen cooled to set the web after leaving apparatus 352. In FIG. 6, theweb 340 is shown to be cooled by blowing cold air onto the web 340 fromblower 370. Of course other known techniques may be used to cool the web340. Cooling the web also solidifies the fused material extending aboutthe perimeter of the apertures.

After cooling, the apertured web 340 is fed through the second nip 380formed by rollers 382 and 384. Rollers 382 and 384 preferably rotate atthe same velocity. Rollers 382 and 384 break the solid fused materialwhich extends about the perimeter of the apertures. Breaking the solidfused material increases the softness of the web 340.

Roller 384 has a smooth outer surface and is preferably constructed of asoft material such as rubber, polyamide, or other polymeric material.The outer surface of roller 382 comprises a plurality of grooves. Roller382 is the same as roller 282 shown in FIG. 5.

The peripheral linear speed of rollers 382 and 384 is preferably greaterthan the peripheral linear speed of rollers 354 and 360 therebytensioning the material between the two sets of rollers. By adjustingthe speeds of the rollers, the material is tensioned such that it necksa desired amount.

From the second nip 380 the web 340 is fed to the third nip 390 formedby rollers 392 and 394. Rollers 392 and 394 preferably rotate at thesame velocity. Rollers 392 and 394 further break the solid fusedmaterial which extends about the perimeter of the apertures. Breakingthe solid fused material increases the softness of the web 340.

Roller 394 has a smooth outer surface and is preferably constructed of asoft material such as rubber, polyamide, or other polymeric material.Referring now to FIG. 7, the outer surface 391 of roller 392 comprises aplurality of grooves 393. Grooves 393 extend about the outer surface 391in a direction different than direction in which the grooves on roller382 extend. Preferably, the grooves 393 extend in a directionperpendicular to the direction in which the grooves on roller 382extend. The grooves 393 are shown in FIG. 7 to be extending in adirection perpendicular to the machine direction. The grooves may alsoextend in other directions. The size, spacing, shape and number ofgrooves may be selected so as to provide the desired softness in the web340 as the grooves help to break the solid fused material which extendsabout the perimeter of the apertures. Roller 382 is preferablyconstructed of steel.

From the third nip 390 the web 340 is wound on take-up roll 398.

Referring now to FIG. 8, there is shown a schematic illustration ofanother process 400 for forming the apertured web of the presentinvention. The process 400 is essentially identical to the processillustrated in FIG. 6, except for the formation of the second and thirdnips 480 and 490. Unlike process 300 illustrated in FIG. 6, process 400utilizes the same smooth roller 484 to form the nips 480 and 490. Thissimply eliminates the need for two smooth rollers. Roller 482 isidentical to roller 282 illustrated in FIG. 5 and roller 492 isidentical to roller 392 illustrated in FIG. 7.

Instead of feeding a single web through the processes illustrated above,multiple webs may be simultaneously fed through the processes. The websmay be identical to one another or different from one another. Forexample, the webs may have different hydrophilicities such that one ismore hydrophilic than the other. The webs may have different dimensionssuch that one web is wider than the other or thicker than the other. Thevarious combinations and number of webs which may be apertured andsoftened according to the present invention may be selected by themanufacturer to provide the desired results.

The diaper 20 may further comprise elasticized leg cuffs (not shown)which provide improved containment of liquids and other body exudates.Each elasticized leg cuff may comprise several different embodiments forreducing the leakage of body exudates in the leg regions. (The leg cuffcan be and is sometimes also referred to as leg bands, side flaps,barrier cuffs, or elastic cuffs.) U.S. Pat. No. 3,860,003 describes adisposable diaper which provides a contractible leg opening having aside flap and one or more elastic members to provide an elasticized legcuff (gasketing cuff). Commonly assigned U.S. Pat. No. 4,909,803entitled “Disposable Absorbent Article Having Elasticized Flaps” issuedto Aziz et al. on Mar. 20, 1990, describes a disposable diaper 20 having“stand-up” elasticized flaps (barrier cuffs) to improve the containmentof the leg regions. Commonly assigned U.S. Pat. No. 4,695,278 entitled“Absorbent Article Having Dual Cuffs” issued to Lawson on Sep. 22, 1987,describes a disposable diaper 20 having dual cuffs including a gasketingcuff and a barrier cuff.

The diaper 20 preferably further comprises an elastic waist feature (notshown) that provides improved fit and containment. The elastic waistfeature is that portion or zone of the diaper 20 which is intended toelastically expand and contract to dynamically fit the wearer's waist.The elastic waist feature at least extends longitudinally outwardly fromat least one of the waist edges of the absorbent core 28 and generallyforms at least a portion of the end edge of the diaper 20. Disposablediapers are generally constructed so as to have two elastic waistfeatures, one positioned in the first waist region 27 and one positionedin the second waist region 29, although diapers can be constructed witha single elastic waist feature. Further, while the elastic waist featureor any of its constituent elements can comprise a separate elementaffixed to the diaper 20, the elastic waist feature is preferablyconstructed as an extension of other elements of the diaper 20 such asthe backsheet 26 or the topsheet 24, preferably both the backsheet 26and the topsheet 24. The elasticized waistband may be constructed in anumber of different configurations including those described in U.S.Pat. No. 4,515,595 issued to Kievit et al. on May 7, 1985 and the abovereferenced U.S. patent application Ser. No. 07/715,152; each of thesereferences being incorporated herein by reference.

The diaper 20 also comprises a fastening system 36 which forms a sideclosure which maintains the first waist region 27 and the second waistregion 29 in an overlapping configuration such that lateral tensions aremaintained around the circumference of the diaper 20 to maintain thediaper 20 on the wearer. Exemplary fastening systems are disclosed inU.S. Pat. No. 4,846,815 entitled “Disposable Diaper Having An ImprovedFastening Device” issued to Scripps on Jul. 11, 1989; U.S. Pat. No.4,894,060 entitled “Disposable Diaper With Improved Hook FastenerPortion” issued to Nestegard on Jan. 16, 1990; commonly assigned U.S.Pat. No. 4,946,527 entitled “Pressure-Sensitive Adhesive Fastener AndMethod of Making Same” issued to Battrell on Aug. 7, 1990; commonlyassigned U.S. Pat. No. 3,848,594 entitled “Tape Fastening System forDisposable Diaper” issued to Buell on Nov. 19, 1974; commonly assignedU.S. Patent B1 4,662,875 entitled “Absorbent Article” issued to Hirotsuet al. on May 5, 1987; and the hereinbefore referenced U.S. patentapplication Ser. No. 07/715,152; each of which is incorporated herein byreference.

The diaper 20 is preferably applied to a wearer by positioning one ofthe waist regions, preferably the second waist region 29, under thewearer's back and drawing the remainder of the diaper 20 between thewearer's legs so that the other waist region, preferably the first waistregion 27, is positioned across the front of the wearer. The tape tabs36 of the fastening system are then released from the release portion.The diaperer then wraps the elasticized side panel around the wearer,while still grasping the tab portion. The fastening system is secured tothe outer surface of the diaper 20 to effect two side closure.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A method of forming an apertured web, said methodcomprising the steps of: a) feeding a web in a machine direction througha first nip formed by a pair of rollers one of said rollers having asmooth outer surface and the other roller having an outer surface with aplurality of projections extending from said outer surface, at least oneof said rollers being heated, such that said web is apertured with aplurality of apertures with the web removed and a fuse perimeter; b)cooling said web to solidify said fused perimeter of said apertures; andc) feeding said web through a second nip formed by a pair of rollers tobreak said solidified fused perimeter of said apertures, one of saidrollers of said second nip having an outer surface with a plurality ofgrooves.
 2. The method of claim 1 comprising the additional step of: d)feeding said web through a third nip formed by a pair of rollers tobreak said solidified fused perimeter of said apertures, one of saidrollers of said third nip having an outer surface with a plurality ofgrooves.
 3. The method of claim 2 wherein said plurality of grooves onsaid outer surface of said roller forming said second nip extend in afirst direction and said plurality of grooves on said outer surface ofsaid roller forming said third nip extend a direction different fromsaid first direction.
 4. The method of claim 3 wherein said firstdirection is parallel to said machine direction.
 5. The method of claim1 wherein said web comprises a nonwoven web.
 6. The method of claim 1wherein a second web is simultaneously fed through said first and secondnips.
 7. The method of claim 1 wherein the web is cooled by blowing coolair onto the web.
 8. The method of claim 1 wherein one of said rollersforming said second nip has a smooth outer surface.
 9. The method ofclaim 2 wherein one of said rollers forming said third nip has a smoothouter surface.